Work vehicle periphery monitoring system and work vehicle periphery monitoring method

ABSTRACT

A work vehicle periphery monitoring system includes: an alarm range storage unit that stores an alarm range, in which an alarm output is required when an object is present, in a detection range of an object detection device that detects an object present in a periphery of a work vehicle; a work mode determination unit that determines a work mode of the work vehicle; an alarm range changing unit that changes the alarm range in the detection range when it is determined that the work mode is a specific work mode; and an alarm control unit that causes an alarm device to output an alarm when an object is present in the alarm range.

FIELD

The present invention relates to a work vehicle periphery monitoringsystem and a work vehicle periphery monitoring method.

BACKGROUND

In the technical field related to a work vehicle, a periphery monitoringsystem that monitors a situation in the periphery of the work vehicle byusing an object detection device has been known. Patent Literature 1discloses a technology for monitoring the periphery of a work vehicleusing a radar device which is a kind of object detection device.

CITATION LIST Patent Literature

-   Patent Literature 1: JP 2012-256113 A

SUMMARY Technical Problem

When the object detection device detects an object present in theperiphery of the work vehicle, an alarm is output from an alarm deviceprovided in a driver's cab of the work vehicle. In a case where theobject is an obstacle that interferes with a work of the work vehicle,the alarm is output, such that the driver of the work vehicle canrecognize that the obstacle is present in the periphery of the workvehicle. On the other hand, in a case where the object that is presentin the periphery of the work vehicle is an object necessary for the workof the work vehicle, when the object detection device detects the objectas an obstacle, an unnecessary alarm is output from the alarm deviceeven though the driver is fully aware of the situation in the peripheryof the work vehicle, and as a result, the driver may feel troublesome.Patent Literature 1 discloses switching between activation anddeactivation of a sensor having a predetermined detection rangeaccording to the position (F, N, or R) of a shift lever. However, analarm region is not set within the detection range, and the alarm regioncannot be changed according to the working state, and thus it is notpossible to sufficiently suppress the output of unnecessary alarms.

An aspect of the present invention is to suppress the output ofunnecessary alarms and to output necessary alarms.

Solution to Problem

According to an aspect of the present invention, a work vehicleperiphery monitoring system comprises: an alarm range storage unit thatstores an alarm range, in which an alarm output is required when anobject is present, in a detection range of an object detection devicethat detects an object present in a periphery of a work vehicle; a workmode determination unit that determines a work mode of the work vehicle;an alarm range changing unit that changes the alarm range in thedetection range when it is determined that the work mode is a specificwork mode; and an alarm control unit that causes an alarm device tooutput an alarm when an object is present in the alarm range.

Advantageous Effects of Invention

According to an aspect of the present invention, it is possible tosuppress the output of unnecessary alarms and to output necessaryalarms.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a side view illustrating a work vehicle.

FIG. 2 is a diagram schematically illustrating a shooting region and adetection region of an object detection device.

FIG. 3 is a block diagram illustrating the work vehicle.

FIG. 4 is a diagram schematically illustrating a detection range and analarm range.

FIG. 5 is a diagram schematically illustrating a work of a work vehiclein a specific work mode.

FIG. 6 is a diagram schematically illustrating the work of a workvehicle in a specific work mode.

FIG. 7 is a diagram schematically illustrating a changed alarm rangethat indicates an alarm range after being changed by an alarm rangechanging unit.

FIG. 8 is a diagram illustrating a display example of a display device.

FIG. 9 is a flowchart illustrating a periphery monitoring method.

FIG. 10 is a block diagram illustrating a computer system.

FIG. 11 is a diagram illustrating a state where the work vehicleexecutes a first rearward movement work in a state where an initialalarm range is maintained without changing the alarm range.

FIG. 12 is a diagram illustrating a state where the work vehicleexecutes the first rearward movement work in a state where the alarmrange is changed to the changed alarm range.

FIG. 13 is a diagram illustrating a state where the alarm range ischanged so that an end of the alarm range that is closest to a transportvehicle is away from the transport vehicle.

FIG. 14 is a diagram illustrating a state where the alarm range ischanged so that the end of the alarm range that is closest to thetransport vehicle is away from the transport vehicle.

DESCRIPTION OF EMBODIMENTS

Hereinafter, embodiments according to the present invention will bedescribed with reference to the drawings, but the present invention isnot limited thereto. Components of the embodiments to be described belowcan be combined as appropriate. In addition, some components are notused in some cases.

[Work Vehicle]

FIG. 1 is a side view illustrating a work vehicle 1. The work vehicle 1performs a predetermined work on a work target at a work site. The workvehicle 1 includes working equipment 10, and performs a predeterminedwork by using the working equipment 10. The predetermined work includesat least one of an excavation work or a loading work. The work targetincludes at least one of an excavation target or a loading target. Thework target is an object necessary for the predetermined work of thework vehicle 1. The work vehicle 1 performs the excavation work in whichthe excavation target is excavated and the loading work in which anexcavated object excavated by the excavation work is loaded into theloading target. The loading work includes a discharge work in which theexcavated object is discharged to a discharge target. As the excavationtarget, at least one of a heap of earth, a heap of rocks, coal, or awall is exemplified. The heap of earth is a heap of earth and sand. Theheap of rocks is a heap of rocks or stones. At least one of a transportvehicle, a predetermined area of the work site, a hopper, a beltconveyor, or a crusher is exemplified as the loading target or thedischarge target.

In an embodiment, the work vehicle 1 is a wheel loader 1 which is a kindof articulated work vehicle. The wheel loader 1 is driven by a driver.The wheel loader 1 includes a driver's stand 3 including a driver's cab3R on which the driver boards, and wheels 5 on which tires 6 aremounted.

In the following description, the positional relationship of therespective parts will be described using the terms such as a top-bottomdirection, a vehicle width direction, and a front-rear direction. Thetop-bottom direction refers to a direction orthogonal to a groundcontact surface of the tire 6 that comes into contact with a groundsurface RS. The vehicle width direction refers to a direction parallelto a rotation axis of the wheel 5. The front-rear direction refers to adirection orthogonal to the top-bottom direction and the vehicle widthdirection.

The term “top” refers to one direction in the top-bottom direction, andmeans a direction in which the driver's cab 3R is present based on theground contact surface of the tire 6. The term “bottom” refers to adirection opposite to “top” in the top-bottom direction. The term “left”refers to one direction in the vehicle width direction. The term “right”refers to a direction opposite to “left” in the vehicle width direction.The term “front” refers to one direction in the front-rear direction,and refers to a direction in which the working equipment 10 is presentbased on the driver's cab 3R. The term “rear” refers to a directionopposite to “front” in the front-rear direction.

As illustrated in FIG. 1 , the wheel loader 1 includes a vehicle body 2,the driver's stand 3, a traveling device 4, a transmission 7, theworking equipment 10, a boom cylinder 15, and a bucket cylinder 16.

The vehicle body 2 includes a vehicle body front part 2F and a vehiclebody rear part 2R arranged behind the vehicle body front part 2F. Thevehicle body front part 2F and the vehicle body rear part 2R areconnected in a bendable manner via a joint mechanism 9.

The driver's stand 3 is supported by the vehicle body 2. The driver'scab 3R is provided in the driver's stand 3. The wheel loader 1 is drivenby the driver who boards on the driver's cab 3R.

The traveling device 4 supports the vehicle body 2 and travels on theground surface RS. The traveling device 4 includes the wheels 5, anengine 4A, a brake 4B, and a steering cylinder 4C. The tire 6 is mountedon the wheel 5.

The wheels 5 include two front wheels 5F rotatably supported by thevehicle body front part 2F and two rear wheels 5R rotatably supported bythe vehicle body rear part 2R. The tires 6 include front tires 6Fmounted on the front wheels 5F and rear tires 6R mounted on the rearwheels 5R.

The vehicle width direction of the vehicle body 2 includes the vehiclewidth direction of the vehicle body front part 2F that is parallel to arotation axis FX of the front wheel 5F and the vehicle width directionof the vehicle body rear part 2R that is parallel to a rotation axis RXof the rear wheel 5R. When the wheel loader 1 travels straight ahead,the rotation axis FX and the rotation axis RX are parallel to eachother, and the vehicle width direction of the vehicle body front part 2Fand the vehicle width direction of the vehicle body rear part 2R are thesame as each other.

The steering cylinder 4C is a hydraulic cylinder that generates power toswing the wheel loader 1. The steering cylinder 4C is provided in thejoint mechanism 9. As the steering cylinder 4C extends and retracts, thevehicle body front part 2F is bent with respect to the vehicle body rearpart 2R. As the vehicle body front part 2F is bent with respect to thevehicle body rear part 2R, the wheel loader 1 swings and a travelingdirection of the wheel loader 1 is adjusted.

The transmission 7 has a plurality of gear stages. In an embodiment, thetransmission 7 has four gear stages. That is, the transmission 7 hasfirst, second, third, and fourth gear stages. As the gear stage of thetransmission 7 is changed, a gear ratio indicating a ratio between therotation speed of an input shaft and the rotation speed of an outputshaft of the transmission 7 is changed. Further, the transmission 7switches a rotation direction of the output shaft with respect to arotation direction of the input shaft. As the rotation direction of theoutput shaft of the transmission 7 is switched, the wheel loader 1 movesforward or rearward.

The working equipment 10 is supported by the vehicle body front part 2F.At least a part of the working equipment 10 is arranged in front of thevehicle body front part 2F. The working equipment 10 includes a boom 11,a bucket 12, a bell crank 13, and a link 14.

The boom 11 is rotatably connected to the vehicle body front part 2F.The bell crank 13 is connected to the bucket 12 via the link 14. Thebucket 12 is rotatably connected to a distal end portion of the boom 11.The bucket 12 is a working member having a distal end portion 12B with ablade. The bucket 12 is arranged in front of the front tire 6F.

The boom cylinder 15 is a hydraulic cylinder that generates power tooperate the boom 11. As the boom cylinder 15 extends and retracts, theboom 11 makes upward movement or downward movement.

The bucket cylinder 16 is a hydraulic cylinder that generates power tooperate the bucket 12. As the bucket cylinder 16 extends and retracts,the bucket 12 makes dumping movement or tilting movement. As the bucket12 makes the tilting movement, the bucket 12 scoops the excavatedobject. As the bucket 12 makes the dumping movement, the excavatedobject held in the bucket 12 is discharged from the bucket 12.

[Object Detection Device]

The wheel loader 1 includes a periphery monitoring system 100 thatmonitors the periphery of the wheel loader 1 and makes the driverrecognize a situation in the periphery of the wheel loader 1. Theperiphery monitoring system 100 includes an object detection device 20.

FIG. 2 is a diagram schematically illustrating a shooting region and adetection region of the object detection device 20. The object detectiondevice 20 detects an object present in the periphery of the wheel loader1. As illustrated in FIGS. 1 and 2 , the object detection device 20includes a camera 21 that shoots an object present in the periphery ofthe wheel loader 1 and a non-contact sensor 22 that detects the objectpresent in the periphery of the wheel loader 1 in a non-contact manner.

A plurality of cameras 21 are mounted on the wheel loader 1 and acquireimages of the object present in the periphery of the wheel loader 1. Thecameras 21 are provided on an outer surface of the vehicle body 2 of thewheel loader 1. The cameras 21 include a camera 21A provided in thevehicle body front part 2F, and a camera 21B, a camera 21C, a camera21D, a camera 21E, and a camera 21F provided in the vehicle body rearpart 2R. An imaging region of each camera 21 may partially overlap withan imaging region of an adjacent camera 21.

The camera 21A is provided on the outer surface on the front side of thevehicle body front part 2F, and shoots a shooting region SA defined infront of the vehicle body 2.

The camera 21B is provided at a front part of the outer surface on theright side of the vehicle body rear part 2R, and shoots a shootingregion SB defined on the right side of the vehicle body 2.

The camera 21C is provided at a rear part of the outer surface on theright side of the vehicle body rear part 2R, and shoots a shootingregion SC defined on the right side and the rear-right side of thevehicle body 2.

The camera 21D is provided on the outer surface on the rear side of thevehicle body rear part 2R, and shoots a shooting region SD definedbehind the vehicle body 2.

The camera 21E is provided at a rear part of the outer surface on theleft side of the vehicle body rear part 2R, and shoots a shooting regionSE defined on the left side and the rear-left side of the vehicle body2.

The camera 21F is provided at a front part of the outer surface on theleft side of the vehicle body rear part 2R, and shoots a shooting regionSF defined on the left side of the vehicle body 2.

A plurality of non-contact sensors 22 are mounted on the wheel loader 1and detect an object present in the periphery of the wheel loader 1 in anon-contact manner. The non-contact sensors 22 scan the periphery of thewheel loader 1 to detect an object. Detection data of the non-contactsensor 22 includes presence/absence data of the object and position dataof the object. The position data of the object indicates relativepositions of the wheel loader 1 and the object. The relative position tothe object includes a distance to the object. The non-contact sensor 22includes a radar device capable of detecting an object by scanning theperiphery of the wheel loader 1 with radio waves. Note that thenon-contact sensor 22 may include a laser scanner device capable ofdetecting an object by scanning the periphery of the wheel loader 1 witha laser beam. The non-contact sensor 22 may include an ultrasonic sensordevice capable of detecting an object by scanning the periphery of thewheel loader 1 with ultrasonic waves. Note that the non-contact sensor22 is not limited to the radar device, the laser scanner device, and theultrasonic sensor device. In the following description, energy wavesused for scanning to detect an object, such as radio waves, a laserbeam, and ultrasonic waves, are referred to as detection waves, asappropriate.

The non-contact sensors 22 are provided on the outer surface of thevehicle body 2 of the wheel loader 1. The non-contact sensors 22 includea non-contact sensor 22A, a non-contact sensor 22B, a non-contact sensor22C, and a non-contact sensor 22D provided at the vehicle body rear part2R. Each of detection regions DA to DD of the non-contact sensors 22A to22D may partially overlap with a detection region of an adjacentnon-contact sensor 22.

The non-contact sensor 22A is provided at the rear part of the outersurface on the right side of the vehicle body rear part 2R, and detectsan object in the detection region DA defined on the right side of thevehicle body 2. The detection region DA extends radially to the rightfrom the non-contact sensor 22A.

The non-contact sensor 22B is provided at a right part of the outersurface on the rear side of the vehicle body rear part 2R, and detectsan object in the detection region DB defined behind and on the rear-leftside of the vehicle body 2. The detection region DB extends radially tothe rear-left side from the non-contact sensor 22B.

The non-contact sensor 22C is provided at a left part of the outersurface on the rear side of the vehicle body rear part 2R, and detectsan object in the detection region DC defined at the rear side and therear-right side of the vehicle body 2. The detection region DC extendsradially to the rear-right side from the non-contact sensor 22C.

The non-contact sensor 22D is provided at the rear part of the outersurface on the left side of the vehicle body rear part 2R, and detectsan object in the detection region DD defined on the left side of thevehicle body 2. The detection region DD extends radially to the leftfrom the non-contact sensor 22D.

In the following description, the detection region DA, the detectionregion DB, the detection region DC, and the detection region DD arecollectively referred to as the detection region D, as appropriate. Thedetection region D is a region to be scanned with the detection waves.

A point included in the detection region of any of the non-contactsensors 22A to 22D corresponds to the detection region D of all of thenon-contact sensors 22. A detection range setting unit 74 as describedlater sets a detection range TD in the detection region D. Further, analarm range specifying unit 75 as described later specifies an alarmrange TA in the detection region D.

The detection regions DA to DD of the respective non-contact sensors 22Ato 22D are not simply fan-shaped regions, but are regions of which leftand right ends are partially cut out. This is to prevent, for example,an end portion of the working equipment from being caught on endportions of the detection regions DA and DD of the non-contact sensors22A and 22D at opposite ends and thus being erroneously recognized as anobstacle, when swinging. In addition, this is because the wheel loader 1is articulated type work machine, and when the wheel loader 1 is steeredto swing to the maximum, the working equipment is tilted greatly withrespect to the vehicle body rear part, and an end portion of the workingequipment may be caught on the end portions of the detection regions DAand DD. The configuration in which the detection regions DA to DD of thenon-contact sensors 22A to 22D are regions of which end portions arepartially cut out is not limited to the articulated type work machine,but can also be applied to, for example, a non-contact sensor providedin an excavator and a forklift. Therefore, it is possible to prevent thenon-contact sensor from erroneously detecting the working equipmentduring the swinging of the excavator and the forklift.

The object detection device 20 can detect an object present in each ofdifferent regions in the periphery of the wheel loader 1 by using theplurality of cameras 21 and the plurality of non-contact sensors 22.

[Periphery Monitoring System]

FIG. 3 is a block diagram illustrating the wheel loader 1. The wheelloader 1 includes an operation device 30 operated by the driver, asensor 40 that detects the state of the wheel loader 1, a vehiclecontrol device 60, and the periphery monitoring system 100. Theperiphery monitoring system 100 includes the object detection device 20,a monitoring control device 70, and a monitor device 50. Each of thevehicle control device 60 and the monitoring control device 70 includesa computer system and is mounted on the wheel loader 1. The vehiclecontrol device 60 controls the traveling device 4, the transmission 7,and the working equipment 10. The monitoring control device 70 controlsthe monitor device 50.

<Operation Device>

The operation device 30 is arranged in the driver's cab 3R and isoperated by the driver. The operation device 30 includes a travelingoperation device 31, a transmission operation device 32, a parking brakeoperation device 33, and a working equipment operation device 34.

The traveling operation device 31 is operated to activate the travelingdevice 4. The traveling operation device 31 includes an acceleratorpedal, a brake pedal, and a steering lever. As the accelerator pedal isoperated, the engine 4A generates a driving force. As the brake pedal isoperated, the brake 4B generates a braking force. As the steering leveris operated, the steering cylinder 4C extends and retracts, and thewheel loader 1 swings.

The transmission operation device 32 is operated to activate thetransmission 7. The transmission operation device 32 includes aforward/rearward movement switch, a shift-up switch, and a shift-downswitch. As the forward/rearward movement switch is operated, therotation direction of the output shaft of the transmission 7 isswitched, and the wheel loader 1 moves forward or rearward. As at leastone of the shift-up switch or the shift-down switch is operated, thegear stage of the transmission 7 is changed. As the shift-up switch isoperated, the gear stage of the transmission 7 is raised and the gearratio of the transmission 7 is reduced. As the shift-down switch isoperated, the gear stage of the transmission 7 is lowered, and the gearratio of the transmission 7 is increased. Note that the function of eachof the forward/rearward movement switch, the shift-up switch, and theshift-down switch may be exhibited by operating one operation member(operation lever or the like).

The parking brake operation device 33 is operated to activate a parkingbrake 8 of the wheel loader 1. The parking brake operation device 33includes a parking brake switch. As the parking brake switch isoperated, the parking brake 8 generates a braking force.

The working equipment operation device 34 is operated to activate theworking equipment 10. The working equipment operation device 34 includesa boom lever and a bucket lever. As the boom lever is operated, the boomcylinder 15 extends and retracts to activate the boom 11. As the bucketlever is operated, the bucket cylinder 16 extends and retracts toactivate the bucket 12.

<Sensor>

The sensor 40 includes a speed sensor 41, a posture sensor 42, an anglesensor 43, and a weight sensor 44.

The speed sensor 41 detects the traveling speed of the wheel loader 1.The speed sensor 41 detects the traveling speed of the wheel loader 1 bydetecting, for example, the rotation speed of the wheel 5 per unit time.

The posture sensor 42 detects the posture of the vehicle body 2. Theposture of the vehicle body 2 includes at least one of the inclinationangle or the angular velocity of the vehicle body 2 with respect to ahorizontal plane. Further, the posture of the vehicle body 2 includes anorientation indicating a direction in which the vehicle body 2 faces.The posture sensor 42 includes an inertial measurement unit (IMU)provided on the vehicle body 2.

The angle sensor 43 detects the angle of the working equipment 10. Theangle sensor 43 includes a boom angle sensor that detects the angle ofthe boom 11 with respect to a reference axis of a vehicle bodycoordinate system defined on the vehicle body front part 2F, and abucket angle sensor that detects the angle of the bucket 12 with respectto the boom 11. The angle sensor 43 may be a potentiometer or a strokesensor that detects the stroke of the boom cylinder 15 and the stroke ofthe bucket cylinder 16.

The weight sensor 44 detects the weight of the bucket 12. The weightsensor 44 detects the weight of the bucket 12 and detects the weight ofthe excavated object held in the bucket 12. Further, the weight sensor44 detects the weight of the bucket 12 and detects whether or not theexcavated object is held in the bucket 12.

<Monitor Device>

The monitor device 50 is arranged in the driver's cab 3R. The monitordevice 50 includes an alarm device 51 and a display device 52.

The alarm device 51 outputs an alarm. The alarm device 51 includes, forexample, a buzzer device, and outputs an alarm sound as an alarm. Thealarm device 51 may include a light emitting device such as a lamp andoutput light as an alarm. The alarm device 51 outputs an alarm, forexample, when the non-contact sensor 22 detects an object present in thealarm range TA.

The display device 52 displays display data. The display device 52includes a flat panel display such as a liquid crystal display (LCD) oran organic electroluminescence (EL) display (OLED). The display device52 displays, as the display data, image data of the periphery of thewheel loader 1, the image data being acquired by the camera 21. Further,when an obstacle is present in the periphery of the wheel loader 1, thedisplay device 52 displays, as the display data, position data of theobstacle detected by the non-contact sensor 22. The display device 52displays the position data of the detected obstacle, for example, whenthe non-contact sensor 22 detects the obstacle present in the detectionrange TD or the alarm range TA.

<Vehicle Control Device>

The vehicle control device 60 is connected to the operation device 30.When the operation device 30 is operated by the driver, the operationdevice 30 outputs operation data. The operation data output from theoperation device 30 is output to the vehicle control device 60. Thevehicle control device 60 outputs a control command for controlling atleast one of the traveling device 4, the transmission 7, the parkingbrake 8, or the working equipment 10, on the basis of the operation dataof the operation device 30.

The vehicle control device 60 includes a traveling control unit 61, atransmission control unit 62, a parking brake control unit 63, and aworking equipment control unit 64.

The traveling control unit 61 outputs a control command for controllingat least one of the engine 4A, the brake 4B, or the steering cylinder4C, on the basis of the operation data output from the travelingoperation device 31.

The transmission control unit 62 outputs a control command forcontrolling the rotation direction of the output shaft of thetransmission 7 and a control command for controlling the gear stage ofthe transmission 7, on the basis of the operation data output from thetransmission operation device 32.

The parking brake control unit 63 outputs a control command forcontrolling the parking brake 8, on the basis of the operation dataoutput from the parking brake operation device 33.

The working equipment control unit 64 outputs a control command forcontrolling at least one of the boom cylinder 15 or the bucket cylinder16, on the basis of the operation data output from the working equipmentoperation device 34.

<Monitoring Control Device>

The monitoring control device 70 is connected to the object detectiondevice 20, the operation device 30, and the sensor 40. The monitoringcontrol device 70 outputs a control command for controlling the monitordevice 50, on the basis of at least one of periphery data indicating thedetection data of the object detection device 20, the operation data ofthe operation device 30, or state data indicating the detection data ofthe sensor 40.

The monitoring control device 70 includes an operation data acquisitionunit 71, a state data acquisition unit 72, a periphery data acquisitionunit 73, a detection range setting unit 74, an alarm range specifyingunit 75, a work mode determination unit 76, an alarm range changing unit77, an obstacle determination unit 78, an alarm control unit 79, adisplay control unit 80, and an alarm range storage unit 81.

The operation data acquisition unit 71 acquires the operation dataoutput from the operation device 30.

The state data acquisition unit 72 acquires the state data indicatingthe detection data of the sensor 40. The sensor 40 detects the statedata indicating the state of the wheel loader 1. The state data includesat least one of the traveling speed of the wheel loader 1, the postureof the vehicle body 2, the angle of the working equipment 10, or theweight of the bucket 12.

The periphery data acquisition unit 73 acquires the periphery dataindicating the detection data of the object detection device 20. Theobject detection device 20 detects periphery data indicating thesituation in the periphery of the wheel loader 1. The periphery dataincludes presence/absence data of an object and position data of theobject present in the periphery of the wheel loader 1, the object beingdetected by the non-contact sensor 22.

The detection range setting unit 74 sets the detection range TD for theobject in the detection region D scanned with the detection waves. Thedetection range TD refers to a target monitoring range for the object.As illustrated in FIG. 2 , the detection range TD is defined as a partof the detection region D. An end portion of the detection region D thatis farthest from the non-contact sensor 22 is, for example, 50 [m] ormore away from the non-contact sensor 22. At the end portion of thedetection region D, the energy of the detection waves is small, and thusobject detection accuracy may decrease. Further, in a case where theentire detection region D is set as the target monitoring range, even anobject that is unlikely to come into contact with the wheel loader 1 isdetected. Further, in a case where the entire detection region D is setas the target monitoring range, the number of data to be processed bythe monitoring control device 70 becomes excessively large. Therefore,from the viewpoint of suppressing a decrease in detection accuracy andsuppressing an increase in the number of data, a detection range TD thatis smaller than the detection region D is set as the target monitoringrange for the object. When detecting an object present in the peripheryof the wheel loader 1, only detection data of an object present in thedetection range TD is adopted, and detection data of an object presentoutside the detection range TD is deleted.

The alarm range specifying unit 75 specifies the alarm range TA in whichan alarm output is required when an object is present. The alarm rangespecifying unit 75 specifies the alarm range TA in the detection rangeTD. Specifying the alarm range TA includes a case where the alarm rangeis set in advance and a case where the alarm range is newly set by aninput/output means (not illustrated), and “specifying” of the alarmrange is a concept including “setting”.

The alarm range storage unit 81 stores data of the alarm range TAspecified by the alarm range specifying unit 75. The data of the alarmrange TA may be stored in a predetermined storage region (notillustrated), or may be input to a predetermined location in a programof the monitoring control device 70. The alarm range TA in an initialstate may be stored in the alarm range storage unit 81, or the alarmrange TA may be set/updated by any setting work.

FIG. 4 is a diagram schematically illustrating the detection range TDand the alarm range TA. As illustrated in FIGS. 2 and 4 , the detectionrange TD is set as a part of the detection region D.

The detection range setting unit 74 defines the detection range TD ofthe non-contact sensor 22 in at least a portion in the periphery of thewheel loader 1. In an embodiment, the detection range setting unit 74defines the detection range TD of the non-contact sensor 22 behind apredetermined portion of the wheel loader 1. The predetermined portionis defined as at least a portion of the vehicle body rear part 2R. In anembodiment, the predetermined portion is defined as a portion of thevehicle body rear part 2R that overlaps with a rear end portion of therear tire 6R in the front-rear direction. The detection range TD isdefined behind the rear end portion of the rear tire 6R. Note that thepredetermined portion is defined as a portion of the vehicle body rearpart 2R that overlaps with the rotation axis RX of the rear tire 6R inthe front-rear direction. Further, the detection range TD is definedbilaterally-symmetrically with respect to a center line CL of the wheelloader 1. The center line CL is a line extending in the front-reardirection through the center of the wheel loader 1 in the vehicle widthdirection.

The detection range TD is defined to have a square shape. In the vehiclewidth direction, a distance between the center line CL and a left end ofthe detection range TD is equal to a distance between the center line CLand a right end of the detection range TD. A front end of the detectionrange TD is parallel to the rotation axis RX. A rear end of thedetection range TD is parallel to the front end of the detection rangeTD. The left end and the right end of the detection range TD areorthogonal to the front end and the rear end of the detection range TD,respectively.

The alarm range specifying unit 75 sets the alarm range TA in thedetection range TD. The alarm range TA is a range in which an alarmoutput is required when an object is present. When an object is presentin the alarm range TA, an alarm is output from the alarm device 51. Whenan object is outside the alarm range TA, even in a case where an objectis present in the detection range TD, the alarm device 51 does notoutput an alarm.

The alarm range TA is defined to have a square shape. A front end of thealarm range TA is parallel to the rotation axis RX. A rear end of thealarm range TA is parallel to the front end of the alarm range TA. Leftand right ends of the alarm range TA are orthogonal to the front andrear ends of the alarm range TA, respectively.

In the front-rear direction, the position of the front end of the alarmrange TA and the position of the front end of the detection range TDoverlap each other. In the front-rear direction, the rear end of thealarm range TA is arranged in front of the rear end of the detectionrange TD. In the vehicle width direction, a distance between the centerline CL and the left end of the alarm range TA is equal to a distancebetween the center line CL and the right end of the alarm range TA. Inthe vehicle width direction, the left end of the alarm range TA isarranged between the center line CL and the left end of the detectionrange TD. In the vehicle width direction, the right end of the alarmrange TA is arranged between the center line CL and the right end of thedetection range TD.

The alarm range specifying unit 75 sets an initial alarm range TA0indicating the initial state of the alarm range TA. A dimension of theinitial alarm range TA0 indicates an initial value of a dimension of thealarm range TA. As illustrated in FIG. 4 , a dimension W of the initialalarm range TA0 in the vehicle width direction is a dimension W0, thedimension W being set by the alarm range specifying unit 75, and adimension L of the initial alarm range TA0 in the front-rear directionis a dimension L0, the dimension L being set by the alarm rangespecifying unit 75.

The work mode determination unit 76 determines a work mode of the wheelloader 1. The work mode determination unit 76 determines whether or notthe work mode of the wheel loader 1 is a specific work mode.

FIGS. 5 and 6 are each a diagram schematically illustrating a work ofthe wheel loader 1 in the specific work mode. The wheel loader 1 canperform the excavation work in which the excavation target is excavatedusing the bucket 12 of the working equipment 10 and the loading work inwhich the excavated object scooped using the bucket 12 in the excavationwork is loaded into the loading target. As the excavation target, theheap of earth DS placed on the ground surface RS is exemplified. As theloading target, a transport vehicle LS is exemplified. As the transportvehicle LS, a dump truck including a dumping bed is exemplified.

As illustrated in FIG. 5(A), the wheel loader 1 performs a first forwardmovement work F1 to move forward toward the heap of earth DS in order toexcavate the heap of earth DS by using the bucket 12 of the workingequipment 10, in a state where the excavated object is not held in thebucket 12 of the working equipment 10. The driver operates the operationdevice 30 to move the wheel loader 1 forward to approach the heap ofearth DS as indicated by the arrow in FIG. 5(A). In addition, the driveroperates the operation device 30 so that the heap of earth DS isexcavated with the bucket 12.

As illustrated in FIG. 5(B), after excavating the heap of earth DS withthe bucket 12 and scooping the excavated object with the bucket 12, thewheel loader 1 performs a first rearward movement work R1 to moverearward so as to be away from the heap of earth DS, in a state wherethe excavated object is held in the bucket 12. The driver operates theoperation device 30 to move the wheel loader 1 rearward to be away fromthe heap of earth DS as indicated by the arrow in FIG. 5(B).

Next, as illustrated in FIG. 6(A), the wheel loader 1 performs a secondforward movement work F2 to move forward toward the transport vehicle LSin order to load the excavated object held in the bucket 12 of theworking equipment 10 into the transport vehicle LS. The driver operatesthe operation device 30 to move the wheel loader 1 forward whileswinging to approach the transport vehicle LS as indicated by the arrowin FIG. 6(A). Further, the driver operates the operation device 30 sothat the excavated object held in the bucket 12 is loaded into a dumpingbed of the transport vehicle LS. That is, the driver operates theoperation device 30 so that the boom 11 makes upward movement in a statewhere the wheel loader 1 moves forward so as to approach the transportvehicle LS. After the boom 11 makes upward movement and the bucket 12 isplaced above the dumping bed of the transport vehicle LS, the driveroperates the operation device 30 so that the bucket 12 is tilted. As aresult, the excavated object is discharged from the bucket 12 and loadedinto the transport vehicle LS.

As illustrated in FIG. 6(B), after the excavated object is dischargedfrom the bucket 12 and loaded into the dumping bed of the transportvehicle LS, the wheel loader 1 performs a second rearward movement workR2 to move rearward so as to be away from the transport vehicle LS, in astate where the excavated object is not held in the bucket 12 of theworking equipment 10. The driver operates the operation device 30 tomove the wheel loader 1 rearward to be away from the transport vehicleLS, as indicated by the arrow in FIG. 6(B).

The driver repeats the above operation until the dumping bed BE is fullof excavated objects. In the following description, a work modeincluding a series of works such as the first forward movement work F1,the first rearward movement work R1, the second forward movement workF2, and the second rearward movement work R2 is referred to as a V-shapework mode as appropriate.

The specific work mode includes the first rearward movement work R1 ofthe V-shape work mode. The work mode determination unit 76 determineswhether or not the wheel loader 1 performs the first rearward movementwork R1 in the V-shape work mode. In the first rearward movement workR1, the wheel loader 1 moves rearward in the periphery of the transportvehicle LS. After moving rearward in the periphery of the transportvehicle LS, the wheel loader 1 performs the second forward movement workF2 to load the excavated object held in the bucket 12 of the workingequipment 10 into the transport vehicle LS.

The work mode determination unit 76 determines the work mode at least onthe basis of the operation data of the transmission operation device 32that is acquired by the operation data acquisition unit 71. When it isdetermined that the wheel loader 1 moves rearward at a specific gearstage on the basis of the operation data of the transmission operationdevice 32 that is acquired by the operation data acquisition unit 71,the work mode determination unit 76 determines that the work mode of thewheel loader 1 is the specific work mode. In an embodiment, in a casewhere the gear stage of the transmission 7 is a low gear stage, the workmode determination unit 76 determines that the work mode of the wheelloader 1 is the specific work mode. In an embodiment, the low gear stagemeans that the gear stage of the transmission 7 is the first gear stageor the second gear stage.

When working in the V-shape work mode, the driver often operates thetransmission operation device 32 so that the gear stage of thetransmission 7 is set to the second gear stage. In a case of performingthe first forward movement work F1 and the second forward movement workF2 in the V-shape work mode, the driver operates the transmissionoperation device 32 so that the wheel loader 1 moves forward in a statewhere the gear stage of the transmission 7 is set to the second gearstage. Further, in a case of performing the first rearward movement workR1 and the second rearward movement work R2 in the V-shape work mode,the driver operates the transmission operation device 32 so that thewheel loader 1 moves rearward in a state where the gear stage of thetransmission 7 is set to the second gear stage. The wheel loader 1performs the first forward movement work F1, the first rearward movementwork R1, the second forward movement work F2, and the second rearwardmovement work R2 in a state where the gear stage is set to the secondgear stage, in the V-shape work mode.

On the other hand, when working in a work mode other than the V-shapework mode, the driver often operates the transmission operation device32 so that the gear stage of the transmission 7 is set to the third orfourth gear stage. In a case of moving the wheel loader 1 forward in awork mode other than the V-shape work mode, the driver operates thetransmission operation device 32 so that the wheel loader 1 movesforward in a state where the gear stage of the transmission 7 is set tothe third or fourth gear stage. In a case of moving the wheel loader 1rearward in a work mode other than the V-shape work mode, the driveroperates the transmission operation device 32 so that the wheel loader 1moves rearward in a state where the gear stage of the transmission 7 isset to the third or fourth gear stage. The wheel loader 1 moves forwardor rearward in a state where the gear stage is set to the third orfourth gear stage, in a work mode other than the V-shape work mode.

Therefore, when it is determined that the wheel loader 1 moves rearwardat the second gear stage, the work mode determination unit 76 candetermine that the work mode of the wheel loader 1 is the first rearwardmovement work R1 of the V-shape work mode.

When the work mode determination unit 76 determines that the work modeof the wheel loader 1 is the specific work mode, the alarm rangechanging unit 77 changes the alarm range TA in the detection range TD.The alarm range changing unit 77 changes the alarm range TA in thedetection range TD so that the alarm range TA does not protrude from thedetection range TD. The change of the alarm range TA includes at leastone of a change of the area of the alarm range TA, a change of theposition of the alarm range TA, or a change of the shape of the alarmrange TA. When the alarm range changing unit 77 changes the alarm rangeTA, data of the alarm range TA stored in the alarm range storage unit 81is updated to data of the changed alarm range TA. Further, when apredetermined condition that the work mode of the wheel loader 1 is thespecific work mode is satisfied, the alarm range changing unit 77updates the data of the alarm range TA stored in the alarm range storageunit 81 to the data of the changed alarm range TA. However, when thepredetermined condition is not satisfied, the alarm range changing unit77 may update the data of the changed alarm range TA to the data of thealarm range TA before the change.

FIG. 7 is a diagram schematically illustrating a changed alarm range TA1that indicates the alarm range TA after being changed by the alarm rangechanging unit 77. As illustrated in FIG. 7 , when it is determined thatthe wheel loader 1 performs the first rearward movement work R1 in theV-shape work mode, the alarm range changing unit 77 changes the alarmrange TA (initial alarm range TA0) so that the dimension W in thevehicle width direction is smaller than the initial dimension W0. Adimension W1 of the changed alarm range TA1 in the vehicle widthdirection is smaller than the dimension W0 of the initial alarm rangeTA0 in the vehicle width direction, the changed alarm range TA1indicating the alarm range TA after being changed by the alarm rangechanging unit 77, and the initial alarm range TA0 being set by the alarmrange specifying unit 75.

Note that the alarm range changing unit 77 does not change the dimensionL of the alarm range TA in the front-rear direction. That is, thedimension L1 of the changed alarm range TA1 in the front-rear directionis equal to the dimension L0 of the initial alarm range TA0 in thefront-rear direction.

The alarm range changing unit 77 sets the changed alarm range TA1 tohave a square shape. A front end of the changed alarm range TA1 overlapswith the front end of the detection range TD. In the vehicle widthdirection, a distance between the center line CL and a left end of thechanged alarm range TA1 is equal to a distance between the center lineCL and a right end of the changed alarm range TA1.

The obstacle determination unit 78 acquires, from the periphery dataacquisition unit 73, the periphery data indicating the detection data ofthe non-contact sensor 22. The obstacle determination unit 78 determineswhether or not an object (obstacle) is present in the alarm range TA. Ina case where the alarm range TA is not changed by the alarm rangechanging unit 77, the obstacle determination unit 78 determines whetheror not an object is present in the initial alarm range TA0. In a casewhere the alarm range TA is changed by the alarm range changing unit 77,the obstacle determination unit 78 determines whether or not an objectis present in the changed alarm range TA1.

The outer shape of the obstacle is smaller than the outer shape of thewheel loader 1. As the obstacle, a manned vehicle such as a pickup truckthat manages a work site is exemplified.

When the obstacle determination unit 78 determines that an object ispresent in the alarm range TA, the alarm control unit 79 outputs, as acontrol command, an alarm command for causing the alarm device 51 tooutput an alarm. As an alarm is output from the alarm device 51, thedriver can recognize that an obstacle is present in the alarm range TA.

The alarm control unit 79 outputs the alarm command when an object ispresent in the alarm range TA in a state where the wheel loader 1 movesrearward. The alarm control unit 79 does not output the alarm command ina state where the wheel loader 1 moves forward or is stopped. The alarmcontrol unit 79 outputs the alarm command when it is determined that thewheel loader 1 moves rearward and when it is determined that an objectis present in the alarm range TA, on the basis of the operation data ofthe transmission operation device 32. The alarm control unit 79 does notoutput the alarm command when it is determined that the wheel loader 1moves forward, on the basis of the operation data of the transmissionoperation device 32, regardless of the presence/absence of an object inthe alarm range TA. The alarm control unit 79 does not output the alarmcommand when it is determined that the wheel loader 1 is stopped, on thebasis of the operation data of the parking brake operation device 33,regardless of the presence/absence of an object in the alarm range TA.

The display control unit 80 outputs, as a control command, a displaycommand for displaying the display data on the display device 52. Thedisplay control unit 80 causes the display device 52 to display, as thedisplay data, image data acquired by the camera 21 and position data ofan object, the position data being acquired by the non-contact sensor22.

<Display Device>

FIG. 8 is a diagram illustrating a display example of the display device52. As illustrated in FIG. 8 , the display control unit 80 displays acharacter image CG and a bird's eye image BI of the wheel loader 1 in afirst region 52A of a display screen of the display device 52, anddisplays an image showing a region behind the wheel loader 1 in a secondregion 52B of the display screen, the image being shot by the camera21D, and the second region 52B being next to the first region 52A. Notethat FIG. 8 illustrates the display example of the display device 52when the wheel loader 1 moves rearward.

The display control unit 80 displays a line LG indicating a boundarybetween shooting regions SBp, SCp, SDp, SEp, and SFp of the plurality ofcameras 21B, 21C, 21D, 21E, and 21F that acquire image data forgenerating the bird's eye image BI in a manner in which the line LG issuperimposed on the bird's eye image BI.

Further, the display control unit 80 displays lines La, Lb, and Lcindicating distances from an outer edge of the wheel loader 1 in amanner in which the lines La, Lb, and Lc are superimposed on the bird'seye image BI. The outer edge of the wheel loader 1 is a line forming theouter shape of the wheel loader 1 when the wheel loader 1 that is in aposture in which the wheel loader 1 can move straight is viewed fromabove. For example, the line La indicates that a distance from the outeredge of wheel loader 1 is 3 [m], the line Lb indicates that the distancefrom the outer edge of wheel loader 1 is 5 [m], and the line Lcindicates that the distance from the outer edge of wheel loader 1 is 7[m].

Further, the display control unit 80 displays a mark 54 indicatingposition data of an obstacle present in the detection range TD in amanner in which the mark 54 is superimposed on the bird's eye image BI,the obstacle being detected by the non-contact sensor 22. For example,when an obstacle present behind the wheel loader 1 is detected by thenon-contact sensor 22, the display control unit 80 displays the mark 54in a manner in which the mark 54 is superimposed on the obstacledisplayed in the bird's eye image BI, on the basis of position data ofthe obstacle. By doing so, the presence of the obstacle is emphasized,and the driver of the wheel loader 1 can quickly recognize thepresence/absence of the obstacle and the position of the obstacle.

In the second region 52B, an indicator 55 indicating the shooting regionof the camera 21 that is displayed in the second region 52B among theshooting regions of the plurality of cameras 21 is displayed.

Further, in the second region 52B, an icon 56, which is display dataindicating that the alarm device 51 is in a state where an alarm can beoutput, is displayed. When the alarm device 51 is in a state where analarm can be output, the icon 56 is displayed. When the alarm device 51is in a state where an alarm cannot be output, the icon 56 is notdisplayed. Depending on whether or not the icon 56 is displayed, thedriver can recognize whether or not the alarm device 51 can output analarm.

When the wheel loader 1 moves rearward, the display control unit 80displays lines Lf, Lg, and Lh indicating distances from a rear endportion of the wheel loader 1 in a manner in which the lines Lf, Lg, andLh are superimposed on an image obtained by shooting. The rear endportion of the wheel loader 1 can be set as, for example, a rear end ofa rear bumper provided at the rearmost portion of the vehicle body rearpart 2R.

In the following description, a display command for displaying the mark54 indicating position data of an obstacle in a case where the obstacleis present in the detection range TD is referred to as a positiondisplay command as appropriate, and a display command for not displayingthe mark 54 in a case where no obstacle is present in the detectionrange TD is referred to as a normal display command as appropriate.

[Periphery Monitoring Method]

FIG. 9 is a flowchart illustrating a periphery monitoring method. Thedetection range setting unit 74 defines the detection range TD of thenon-contact sensor 22 behind the predetermined portion of the wheelloader 1. The alarm range specifying unit 75 sets the alarm range TA inwhich an alarm output is required when an object is present, in thedetection range TD defined by the detection range setting unit 74.

The operation data acquisition unit 71 acquires operation data generatedby operating the operation device 30 (Step S10).

The operation data acquisition unit 71 acquires the operation data ofthe transmission operation device 32. Further, the operation dataacquisition unit 71 acquires the operation data of the parking brakeoperation device 33.

The work mode determination unit 76 determines whether or not the wheelloader 1 moves rearward on the basis of the operation data of theforward/rearward switch of the transmission operation device 32, theoperation data being acquired by the operation data acquisition unit 71(Step S20).

In a case where it is determined in Step S20 that the wheel loader 1moves rearward (Step S20: Yes), the work mode determination unit 76determines whether or not the transmission 7 is set to the second gearstage which is the specific gear stage on the basis of the operationdata of the shift-up switch and the shift-down switch of thetransmission operation device 32 (Step S30).

When it is determined in Step S30 that the transmission 7 is set to thesecond gear stage (Step S30: Yes), the work mode determination unit 76determines that the work mode of the wheel loader 1 is the specific workmode. The work mode determination unit 76 determines that the wheelloader 1 performs the first rearward movement work R1 in the V-shapework mode. The alarm range changing unit 77 changes the alarm range TAset by the alarm range specifying unit 75 (Step S40).

As described with reference to FIG. 7 , the alarm range changing unit 77changes the initial alarm range TA0 to the changed alarm range TA1 sothat the dimension W in the vehicle width direction decreases.

In a case where it is determined in Step S30 that the transmission 7 isnot set to the second gear stage (Step S30: No), the work modedetermination unit 76 determines that the work mode of the wheel loader1 is a work mode other than the specific work mode. The work modedetermination unit 76 determines that the wheel loader 1 moves rearwardin a work mode other than the V-shape work mode. The alarm rangechanging unit 77 does not change the alarm range TA. The alarm range TAis set to the initial alarm range TA0 set by the alarm range specifyingunit 75 (Step S50).

The obstacle determination unit 78 determines whether or not an object(obstacle) is present in the alarm range TA on the basis of theperiphery data acquired by the periphery data acquisition unit 73 (StepS60).

In a case where the alarm range TA is changed to the changed alarm rangeTA1, the obstacle determination unit 78 determines whether or not anobject is present in the changed alarm range TA1. In a case where thealarm range TA is not changed to the changed alarm range TA1, theobstacle determination unit 78 determines whether or not an object ispresent in the initial alarm range TA0.

In a case where it is determined in Step S60 that an object is presentin the alarm range TA (Step S60: Yes), the alarm control unit 79 outputsthe alarm command for causing the alarm device 51 to output an alarm.Further, the display control unit 80 outputs the position displaycommand for causing the display device 52 to additionally display themark 54 (Step S70).

In a case where it is determined in Step S60 that no object is presentin the alarm range TA (Step S60: No), the obstacle determination unit 78determines whether or not an object is present outside the alarm rangeTA, but inside the detection range TD (Step S80).

In a case where it is determined in Step S80 that no object is presentin the alarm range TA, but an object is present in the detection rangeTD (Step S80: Yes), the display control unit 80 outputs the positiondisplay command for causing the display device 52 to additionallydisplay the mark 54 (Step S90).

Note that in a case where it is determined in Step S80 that an object ispresent in the detection range TD, but no object is present in the alarmrange TA, the alarm control unit 79 does not output the alarm command.

In a case where it is determined in Step S80 that no object is presentin the detection range TD (Step S80: No), the display control unit 80outputs the normal display command for causing the display device 52 notto display the mark 54 (Step S100).

In a case where it is determined in Step S20 that the wheel loader 1does not move rearward (Step S20: No), the alarm range TA is not changedand is set to the initial alarm range TA0 set by the alarm rangespecifying unit 75 (Step S110).

The obstacle determination unit 78 determines whether or not an object(obstacle) is present in the detection range TD on the basis of theperiphery data acquired by the periphery data acquisition unit 73 (StepS120).

In a case where it is determined in step S120 that an object is presentin the detection range TD (Step S120: Yes), the display control unit 80outputs the position display command for causing the display device 52to additionally display the mark 54 (Step S130).

Note that, in Step S130, no alarm command is output from the alarmcontrol unit 79.

In a case where it is determined in Step S120 that no object is presentin the detection range TD (Step S120: No), the display control unit 80outputs the normal display command for causing the display device 52 notto display the mark 54 (Step S140).

[Computer System]

FIG. 10 is a block diagram illustrating a computer system 1000. Each ofthe vehicle control device 60 and the monitoring control device 70described above includes the computer system 1000. The computer system1000 includes a processor 1001 such as a central processing unit (CPU),a main memory 1002 including a non-volatile memory such as a read onlymemory (ROM) and a volatile memory such as a random access memory (RAM),a storage 1003, and an interface 1004 including an input/output circuit.The functions of the vehicle control device 60 and the functions of themonitoring control device 70 described above are stored as a program inthe storage 1003. The processor 1001 reads the program from the storage1003, loads the program to the main memory 1002, and performs theabove-described processing according to the program. Note that theprogram may be distributed to the computer system 1000 via a network.

[Effects]

As described above, when it is determined that the work mode of thewheel loader 1 is the specific work mode, the alarm range TA, in whichan alarm output is required when an object is present, is changed. In anembodiment, the alarm range TA is changed so that the dimension in thevehicle width direction of the wheel loader 1 decreases. As a result, anunnecessary alarm is suppressed from being output from the alarm device51.

FIG. 11 is a diagram illustrating a state where the wheel loader 1performs the first rearward movement work R1 in the V-shape work mode ina state where the alarm range TA is not changed and the initial alarmrange TA0 is maintained. In the first rearward movement work R1, thewheel loader 1 moves rearward in the periphery of the transport vehicleLS. The outer shape of the initial alarm range TA0 is large. Asillustrated in FIG. 11 , in a case where the initial alarm range TA0 ismaintained, there is a high possibility that the transport vehicle LSenters the initial alarm range TA0 when the wheel loader 1 movesrearward in the vicinity of the transport vehicle LS. The transportvehicle LS is not an obstacle, but an object necessary for the work ofthe wheel loader 1.

In a case where the transport vehicle LS enters the initial alarm rangeTA0, the obstacle determination unit 78 erroneously determines that anobstacle is present in the initial alarm range TA0, and the alarmcontrol unit 79 outputs the alarm command for causing the alarm device51 to output an alarm. In the V-shape work mode, the driver performs thefirst rearward movement work R1 while fully recognizing the presence ofthe transport vehicle LS. In a case where the non-contact sensor 22detects the transport vehicle LS as an obstacle, the alarm device 51outputs an unnecessary alarm, even though the driver is fully aware ofthe situation in the periphery of the wheel loader 1. As a result, thedriver may feel troublesome.

FIG. 12 is a diagram illustrating a state where the wheel loader 1performs the first rearward movement work R1 in the V-shape work mode ina state where the alarm range TA is changed to the changed alarm rangeTA1. As illustrated in FIG. 12 , the dimension W1 of the changed alarmrange TA1 in the vehicle width direction is smaller than the dimensionW0 of the initial alarm range TA0 in the vehicle width direction. Asillustrated in FIG. 11 , as the alarm range TA is changed to the changedalarm range TA1, it is possible to suppress the transport vehicle LSfrom entering the changed alarm range TA1 when the wheel loader 1 movesrearward in the periphery of the transport vehicle LS. In the exampleillustrated in FIG. 12 , the transport vehicle LS is present on the leftside of the wheel loader 1 when the first rearward movement work R1 isperformed. The alarm range changing unit 77 changes the alarm range TAso that the end (left end) of the alarm range TA that is closest to thetransport vehicle LS is away from the transport vehicle LS when thewheel loader 1 moves rearward. As a result, it is possible to suppressthe non-contact sensor 22 from detecting the transport vehicle LS as anobstacle in a state where the driver is fully aware of the situation inthe periphery of the wheel loader 1. Therefore, an unnecessary alarm issuppressed from being output from the alarm device 51.

Note that FIG. 12 illustrates an example in which the transport vehicleLS is present on the left side of the wheel loader 1 when the firstrearward movement work R1 is performed. In a case where the transportvehicle LS is on the right side of the wheel loader 1 when the firstrearward movement work R1 is performed, the alarm range changing unit 77changes the alarm range TA so that the end (right end) of the alarmrange TA that is closest to the transport vehicle LS is away from thetransport vehicle LS when the wheel loader 1 moves rearward.

In an embodiment, in the first rearward movement work R1, the dimensionL of the alarm range TA in the front-rear direction is not changed, andthe dimension L1 of the changed alarm range TA1 is equal to thedimension L0 of the initial alarm range TA0. As a result, the dimensionof the alarm range TA behind the vehicle body rear part 2R of the wheelloader 1 is sufficiently maintained. Therefore, in a case where anobstacle is present directly behind the vehicle body rear part 2R, theobstacle determination unit 78 can detect that the obstacle is presentin the alarm range TA. The alarm control unit 79 can output the alarmcommand to the alarm device 51.

When the work mode of the wheel loader 1 is not the specific work mode,the initial alarm range TA0 is maintained as the alarm range TA. As aresult, in a case where an obstacle is present in the periphery of thewheel loader 1 when the driver moves the wheel loader 1 rearward, thealarm control unit 79 can output the alarm command to the alarm device51 to output a necessary alarm.

The detection range TD is defined behind the predetermined portion ofthe wheel loader 1. A region in front of the wheel loader 1 and regionson the sides of the wheel loader 1 are visible to the driver. Further,the wheel loader 1 is an articulated type work vehicle that is bent atthe joint mechanism 9, and the predetermined portion is defined as atleast a portion of the vehicle body rear part 2R. Therefore, forexample, in a case where the non-contact sensor 22 that scans adiagonally front side is arranged on the outer surface on the left sideor the right side of the vehicle body rear part 2R, there is apossibility that at least a portion of the vehicle body front part 2Fenters the detection region of the non-contact sensor 22 when thevehicle body front part 2F is bent via the joint mechanism 9. Therefore,the detection range TD does not have to be defined in the region infront of the wheel loader 1 and the regions on the sides of the wheelloader 1. Since it is not necessary to provide the non-contact sensor 22that scans the region in front of the wheel loader 1 and the regions onthe sides of the wheel loader 1, the cost of the wheel loader 1 isreduced.

Further, since the wheel loader 1 is an articulated type work vehiclethat is bent at the joint mechanism 9, when the wheel loader 1 movesrearward while swinging, the front tire 6F can pass through a portionwhere the rear tire 6R passes on the ground surface RS. That is, aninner ring difference of the wheel loader 1 is sufficiently small.Therefore, even in a case where the wheel loader 1 moves rearward in astate where an obstacle is present on the side of the wheel loader 1,the contact between the wheel loader 1 and the obstacle is sufficientlysuppressed.

[Other Embodiments]

In the above-described embodiment, the work mode determination unit 76determines whether or not the wheel loader 1 performs the specific workmode on the basis of the operation data of the transmission operationdevice 32 that operates the transmission 7 included in the wheel loader1. The work mode determination unit 76 may determine the work mode ofthe wheel loader 1 on the basis of the state data detected by the sensor40. Further, the work mode determination unit 76 may determine the workmode of the wheel loader 1 on the basis of at least one of the operationdata of the transmission operation device 32 or the detection data ofthe sensor 40. Further, the work mode determination unit 76 maydetermine the work mode of the wheel loader 1 on the basis of at leastone of the operation data of the traveling operation device 31 or theoperation data of the working equipment operation device 34, in additionto the operation data of the transmission operation device 32.

In the V-shape work mode, the wheel loader 1 repeats a predeterminedoperation in a predetermined order. For example, the traveling speed ofthe traveling device 4, the traveling direction (forward or rearward) ofthe traveling device 4, the posture of the vehicle body 2, the angle ofthe working equipment 10, and the weight of the bucket 12 each change ina predetermined order under predetermined conditions. That is, in thefirst forward movement work F1 of the V-shape work mode, the wheelloader 1 moves forward in a state where the distal end portion 12B ofthe bucket 12 is in contact with the ground surface RS. In the firstrearward movement work R1, the wheel loader 1 moves rearward while thebucket 12 makes tilting movement and the boom 11 makes upward movement.In the second forward movement work F2, the boom 11 makes upwardmovement and the bucket 12 makes dumping movement while the wheel loader1 moves forward. In the second rearward movement work R2, the wheelloader 1 moves rearward while the boom 11 makes downward movement.Further, in the first forward movement work F1 and the second rearwardmovement work R2, the excavated object is not held in the bucket 12, andin the first rearward movement work R1 and the second forward movementwork F2, the excavated object is held in the bucket 12.

In this way, in the V-shape work mode, the wheel loader 1 repeats apredetermined operation in a predetermined order, such that it ispossible to specify the work mode by detecting the state of the wheelloader 1 such as the traveling speed of the traveling device 4, thetraveling direction of the traveling device 4, the posture of thevehicle body 2, the angle of the working equipment 10, and the weight ofthe bucket 12. Therefore, the work mode determination unit 76 candetermine whether or not the wheel loader 1 performs the specific workmode, on the basis of the state data indicating the detection data ofthe sensor 40 including the speed sensor 41 that detects the travelingspeed of the traveling device 4, the posture sensor 42 that detects theposture of the vehicle body 2, the angle sensor 43 that detects theangle of the working equipment 10, and the weight sensor 44 that detectsthe weight of the bucket 12. The work mode determination unit 76 candetermine whether or not the wheel loader 1 performs the specific workmode by combining the operation data of the operation device 30including the transmission operation device 32, and the state datadetected by the sensor 40. In a case where the work mode determinationunit 76 determines whether or not the wheel loader 1 performs thespecific work mode by using the operation data of the operation device30 and the state data detected by the sensor 40, the determination maybe performed by using an artificial intelligence technology such asmachine learning. The work mode determination unit 76 may determinewhether or not the wheel loader 1 performs the specific work modethrough image recognition based on the artificial intelligencetechnology by using imaging data shot by the camera 21.

In the above-described embodiment, the alarm range changing unit 77changes the alarm range TA when it is determined that the work mode ofthe wheel loader 1 is the specific work mode. The alarm range changingunit 77 may change the alarm range TA in the detection range TD on thebasis of the operation data of the transmission operation device 32 thatoperates the transmission 7 regardless of the work mode of the wheelloader 1. The alarm range changing unit 77 may change the alarm range TAwhen it is determined that the wheel loader 1 moves rearward at aspecific gear stage on the basis of the operation data of thetransmission operation device 32. In this case, the work modedetermination unit 76 can be omitted.

Further, the alarm range changing unit 77 may change the alarm range TAin the detection range TD on the basis of the detection data of thesensor 40 that detects the state of the wheel loader 1, regardless ofthe work mode of the wheel loader 1.

As described above, in the V-shape work mode, the gear stage of thetransmission 7 is often set to the second gear stage. Note that, in thefirst forward movement work F1, for example, in a case where the distalend portion 12B of the bucket 12 is inserted into the heap of earth DSand the load on the traveling device 4 increases, the transmissioncontrol unit 62 automatically shifts down the gear stage of thetransmission 7 from the second gear stage to the first gear stage.

In the above-described embodiment, the alarm range TA is changed whenthe specific gear stage is the second gear stage and the wheel loader 1moves rearward at the second gear stage. The specific gear stage mayalso be the first gear stage. For example, in a case where a movementdistance of the wheel loader 1 in each of the first forward movementwork F1, the first rearward movement work R1, the second forwardmovement work F2, and the second rearward movement work R2 of theV-shape work mode is short, the work may be performed in the V-shapework mode in a state where the first gear stage is maintained. In a casewhere the work is performed in the V-shape work mode in a state wherethe first gear stage is maintained, the alarm range changing unit 77 maychange the alarm range TA when the wheel loader 1 moves rearward at thefirst gear stage.

In a case where the work is performed in the V-shape work mode in eachof a state where the gear stage is set to the first gear stage and astate where the gear stage is set to the second gear stage, the alarmrange changing unit 77 may set a dimension W1 of the changed alarm rangeTA1 in the vehicle width direction when the wheel loader 1 movesrearward at the first gear stage to be smaller than a dimension W1 ofthe changed alarm range TA1 in the vehicle width direction when thewheel loader 1 moves rearward at the second gear stage. That is, thealarm range changing unit 77 may set the dimension W1 of the changedalarm range TA1 so as to be different on the basis of the gear stage.

In the above-described embodiment, the alarm range changing unit 77changes the alarm range TA so that the dimension W in the vehicle widthdirection decreases. The alarm range changing unit 77 may change thealarm range TA so that the dimension L in the front-rear directiondecreases, or may change the alarm range TA so that both the dimension Lin the front-rear direction and the dimension W in the vehicle widthdirection become smaller.

In the above-described embodiment, the changed alarm range TA1 is set tobe bilaterally symmetrical with respect to the center line CL of thewheel loader 1. The alarm range changing unit 77 may change the alarmrange TA so that the end of the alarm range TA that is closest to thetransport vehicle LS is away from the transport vehicle LS in the firstrearward movement work R1 of the wheel loader 1.

FIGS. 13 and 14 are each a diagram illustrating a state where the alarmrange TA is changed so that the end of the alarm range TA that isclosest to the transport vehicle LS is away from the transport vehicleLS.

As illustrated in FIG. 13 , in a case where the transport vehicle LS ispresent on the left side of the wheel loader 1 when the first rearwardmovement work R1 is performed, the alarm range changing unit 77 changesthe position of a left end of the initial alarm range TA0 so that theleft end of the changed alarm range TA1 that is closest to the transportvehicle LS is away from the transport vehicle LS when the wheel loader 1moves rearward. In the example illustrated in FIG. 13 , the position ofa right end of the initial alarm range TA0 is not changed, and theposition of the right end of the changed alarm range TA1 is the same asthe position of the right end of the initial alarm range TA0. Also inthe example illustrated in FIG. 13 , an unnecessary alarm is suppressedfrom being output from the alarm device 51.

The alarm range changing unit 77 can determine relative positions of thewheel loader 1 and the transport vehicle LS on the basis of theoperation data of the steering lever (traveling operation device 31)that operates the steering cylinder 4C (steering device). As illustratedin FIG. 13 , in a case where the transport vehicle LS is present on theleft side of the wheel loader 1 in the first rearward movement work R1,at least the steering lever is operated so that the wheel loader 1 movesrearward while swinging to the right. In a case where the transportvehicle LS is present on the right side of the wheel loader 1 in thefirst rearward movement work R1, at least the steering lever is operatedso that the wheel loader 1 moves rearward while swinging to the left.Therefore, the alarm range changing unit 77 can determine whether thetransport vehicle LS is present on the left side of the wheel loader 1or the right side of the wheel loader 1 on the basis of at least theoperation data of the steering lever, and can change the alarm range TAso that the end of the alarm range TA that is closest to the loadingvehicle LS is away from the loading vehicle LS when the wheel loader 1moves rearward.

In a case where it is determined that the transport vehicle LS ispresent on the left side of the wheel loader 1 when the first rearwardmovement work R1 is performed, on the basis of at least the operationdata of the steering lever, the alarm range changing unit 77 changes theposition of the left end of the initial alarm range TA0 so that the leftend of the changed alarm range TA1 that is closest to the transportvehicle LS is away from the transport vehicle LS when the wheel loader 1moves rearward. Further, in a case where it is determined that thetransport vehicle LS is present on the right side of the wheel loader 1when the first rearward movement work R1 is performed, on the basis ofat least the operation data of the steering lever, the alarm rangechanging unit 77 changes the position of the right end of the initialalarm range TA0 so that the right end of the changed alarm range TA1that is closest to the transport vehicle LS is away from the transportvehicle LS when the wheel loader 1 moves rearward.

As illustrated in FIG. 14 , in a case where the transport vehicle LS ispresent on the left side of the wheel loader 1 when the first rearwardmovement work R1 is performed, the alarm range changing unit 77 changesthe position of the initial alarm range TA0 so that the left end of thechanged alarm range TA1 that is closest to the transport vehicle LS isaway from the transport vehicle LS when the wheel loader 1 movesrearward. In the example illustrated in FIG. 14 , the size of theinitial alarm range TA0 is not changed, and the area of the changedalarm range TA1 is equal to the area of the initial alarm range TA0. Thechanged alarm range TA1 corresponds to the alarm range TA obtained bymoving the position of the initial alarm range TA0 to the right. Also inthe example illustrated in FIG. 14 , an unnecessary alarm is suppressedfrom being output from the alarm device 51.

In the above-described embodiment, the change of the alarm range TAincludes at least one of a change of the area of the initial alarm rangeTA0, a change of the position of the initial alarm range TA0, or achange of the shape of the initial alarm range TA0. In addition, thechange of the alarm range TA is a concept including removing orinvalidating a part of detection data of an object present in theinitial alarm range TA0 without changing the area, position, and shapeof the initial alarm range TA0.

In the above-described embodiment, the specific work mode in which thealarm range TA is changed is the first rearward movement work R1 of theV-shape work mode. The specific work mode is not limited to the firstrearward movement work R1. For example, in a case where walls arepresent on both sides of a passage of the wheel loader 1 moving rearwardand the wheel loader 1 performs a specific work in which the wheelloader 1 has to move rearward in a narrow passage, the alarm rangechanging unit 77 may change the alarm range TA so that the dimension Win the vehicle width direction decreases.

In the above-described embodiment, the alarm range changing unit 77 maychange the alarm range TA so that one or both of the dimension L in thefront-rear direction and the dimension W in the vehicle width directionincrease. In addition, the alarm range changing unit 77 may change thealarm range TA by sliding the alarm range TA in any one direction,changing the shape of the alarm range TA, bending the alarm range TA, orchanging the aspect ratio of the alarm range TA.

In the above-described embodiment, the detection range TD is definedbehind the predetermined portion of the wheel loader 1. The detectionrange TD may be defined in front of the predetermined portion of thewheel loader 1 or may be defined on the side of the wheel loader 1.

In the above-described embodiment, the specific work mode in which thealarm range TA is changed is the first rearward movement work R1, andthe alarm range TA is changed in the first rearward movement work R1 ofthe wheel loader 1. The specific work mode in which the alarm range TAis changed may be at least one of the first forward movement work F1,the first rearward movement work R1, the second forward movement workF2, or the second rearward movement work R2. For example, in the firstforward movement work F1 or the second forward movement work F2, in acase where there is a possibility that an unnecessary alarm is outputfrom the alarm device 51, the alarm range changing unit 77 can changethe alarm range TA in the first forward movement work F1 or the secondforward movement work F2. Further, in a case where there is apossibility that an unnecessary alarm is output from the alarm device 51in the second rearward movement work R2, the alarm range changing unit77 can change the alarm range TA in the second rearward movement workR2.

In the above-described embodiment, the specific work mode in which thealarm range TA is changed may be the V-shape work mode. That is, thealarm range changing unit 77 may change the alarm range TA when it isdetermined that the wheel loader 1 performs the V-shape work modeincluding the first forward movement work F1 in which the wheel loader 1moves forward toward the excavation target in order to excavate theexcavation target by using the working equipment 10, the first rearwardmovement work R1 in which the wheel loader 1 moves rearward so as to beaway from the excavation target after excavating the excavation target,the second forward movement work F2 in which the wheel loader 1 movesforward toward the loading target in order to load the excavated objectheld in the working equipment 10 into the loading target, and the secondrearward movement work R2 in which the wheel loader 1 moves rearward soas to be away from the loading target after loading the excavated objectinto the loading target.

In the above-described embodiment, the detection range TD is set and thealarm range TA is set in the detection range TD, but the presentinvention is not limited to this embodiment. For example, the detectionrange TD does not have to be set, and a detectable range of thenon-contact sensor 22 may be set as the detection range TD.

The operation of the wheel loader 1 does not have to be performed in thedriver's cab 3R provided in the wheel loader 1, and may be performed,for example, in a remote driver's cab (not illustrated) far away fromthe wheel loader 1. In this case, the operation device 30, the alarmdevice 51, and the display device 52 may be installed in the remotedriver's cab.

Note that, in the above-described embodiment, the work vehicle 1 is notlimited to the wheel loader 1. The work vehicle 1 may be, for example,at least one of a forklift, a dump truck, or a motor grader.

REFERENCE SIGNS LIST

1 WHEEL LOADER (WORK VEHICLE)

2 VEHICLE BODY

2F VEHICLE BODY FRONT PART

2R VEHICLE BODY REAR PART

3 DRIVER'S STAND

3R DRIVER'S CAB

4 TRAVELING DEVICE

4A ENGINE

4B BRAKE

4C STEERING CYLINDER

5 WHEEL

5F FRONT WHEEL

5R REAR WHEEL

6 TIRE

6F FRONT TIRE

6R REAR TIRE

7 TRANSMISSION

8 PARKING BRAKE

9 JOINT MECHANISM

10 WORKING EQUIPMENT

11 BOOM

12 BUCKET

12B DISTAL END PORTION

13 BELL CRANK

14 LINK

15 BOOM CYLINDER

16 BUCKET CYLINDER

20 OBJECT DETECTION DEVICE

21 CAMERA

21A CAMERA

21B CAMERA

21C CAMERA

21D CAMERA

21E CAMERA

21F CAMERA

22 NON-CONTACT SENSOR

22A NON-CONTACT SENSOR

22B NON-CONTACT SENSOR

22C NON-CONTACT SENSOR

22D NON-CONTACT SENSOR

30 OPERATION DEVICE

31 TRAVELING OPERATION DEVICE

32 TRANSMISSION OPERATION DEVICE

33 PARKING BRAKE OPERATION DEVICE

34 WORKING EQUIPMENT OPERATION DEVICE

40 SENSOR

41 SPEED SENSOR

42 POSTURE SENSOR

43 ANGLE SENSOR

44 WEIGHT SENSOR

50 MONITOR DEVICE

51 ALARM DEVICE

52 DISPLAY DEVICE

52A FIRST REGION

52B SECOND REGION

54 MARK

55 INDICATOR

56 ICON

60 VEHICLE CONTROL DEVICE

61 TRAVELING CONTROL UNIT

62 TRANSMISSION CONTROL UNIT

63 PARKING BRAKE CONTROL UNIT

64 WORKING EQUIPMENT CONTROL UNIT

70 MONITORING CONTROL DEVICE

71 OPERATION DATA ACQUISITION UNIT

72 STATE DATA ACQUISITION UNIT

73 PERIPHERY DATA ACQUISITION UNIT

74 DETECTION RANGE SETTING UNIT

75 ALARM RANGE SPECIFYING UNIT

76 WORK MODE DETERMINATION UNIT

77 ALARM RANGE CHANGING UNIT

78 OBSTACLE DETERMINATION UNIT

79 ALARM CONTROL UNIT

80 DISPLAY CONTROL UNIT

81 ALARM RANGE STORAGE UNIT

100 PERIPHERY MONITORING SYSTEM

1000 COMPUTER SYSTEM

1001 PROCESSOR

1002 MAIN MEMORY

1003 STORAGE

1004 INTERFACE

BI BIRD'S EYE IMAGE

CG CHARACTER IMAGE

D DETECTION REGION

DA DETECTION REGION

DB DETECTION REGION

DC DETECTION REGION

DD DETECTION REGION

F1 FIRST FORWARD MOVEMENT WORK

F2 SECOND FORWARD MOVEMENT WORK

FX ROTATION AXIS

L0 DIMENSION

L1 DIMENSION

La LINE

Lb LINE

Lc LINE

Lf LINE

Lg LINE

Lh LINE

LG LINE

R1 FIRST REARWARD MOVEMENT WORK

R2 SECOND REARWARD MOVEMENT WORK

RS GROUND SURFACE

RX ROTATION AXIS

SA SHOOTING REGION

SB SHOOTING REGION

SC SHOOTING REGION

SD SHOOTING REGION

SE SHOOTING REGION

SF SHOOTING REGION

SBp SHOOTING REGION

SCp SHOOTING REGION

SDp SHOOTING REGION

SEp SHOOTING REGION

SFp SHOOTING REGION

TA ALARM RANGE

TA0 INITIAL ALARM RANGE

TA1 CHANGED ALARM RANGE

TD DETECTION RANGE

W0 DIMENSION

W1 DIMENSION

The invention claimed is:
 1. A work vehicle periphery monitoring systemcomprising: an alarm range storage unit that stores a predeterminedalarm range, in which an alarm output is required when an object ispresent, in a detection range of an object detection device that detectsan object present in a periphery of a work vehicle; a work modedetermination unit that determines a work mode of the work vehicle; analarm range changing unit that changes the alarm range in the detectionrange when it is determined that the work mode is a specific work mode;and an alarm control unit that causes an alarm device to output an alarmwhen an object is present in the alarm range, wherein the work modedetermination unit determines that the work mode of the work vehicle isthe specific work mode in a case where a gear stage of a transmissionincluded in the work vehicle is a low gear stage, on a basis ofoperation data of a transmission operation device that operates thetransmission.
 2. The work vehicle periphery monitoring system accordingto claim 1, wherein the predetermined alarm range is an alarm rangedefined behind a predetermined portion of the work vehicle.
 3. A Thework vehicle periphery monitoring system according to claim 1, whereinthe work vehicle is an articulated type work vehicle; and wherein thegear stage of the transmission included in the articulated type workvehicle is a rearward low gear stage.
 4. The work vehicle peripherymonitoring system according to claim 1, wherein the alarm range changingunit changes the alarm range so that a dimension in a vehicle widthdirection of the work vehicle decreases.